New Research: Regulation of hypocotyl growth under different photoperiods

6 Jul 2020
Hypocotyl length of wild-type (WT), cdf5 mutants (cdf5, cdf5-5'UTR) and CDF5-overexpressing seedlings (CDF5-Ox) shows CDF5 regulation only under short day (SD) conditions. Seedlings were grown for 3 days under either SD or long (LD) days. Scale bar corresponds to 5 mm.

Plants are able to elongate their hypocotyls accordingly to day length duration. Here, we elucidate the molecular mechanism controlling this response.

When grown under short days plants will elongate their hypocotyls when trying to reach for light. This response is under the control of specific regulators such as the Phytochrome Interacting Factors (PIFs). These transcription factors accumulate preferably at the end of the night when they promote the expression of regulators of cell expansion. The Monte and Henriques laboratories had previously shown that downstream of PIFs, CDF5 (Cycling DOF Factor 5) was also required for this response (Martin et al 2018).

In this new publication, they expand on previous knowledge and show that, although CDF5 accumulates under both short (8h light/16h dark) and long (16h light/ 8h dark) days, it only promotes hypocotyl elongation under the former (Martin et al 2020). Interestinlgy, it was observed that CDF1, a close relative to CDF5, could also be involved in this response. These findings highlight the multiple biological functions of CDFs and further confirm their role at the intersection between circadian-regulated functions and light-responsive processes.

School of Biological, Earth and Environmental Sciences

An Scoil Eolaíochtaí Bitheolaíocha, Domhaneolaíocha agus Comhshaoil

University College Cork, Distillery Fields, North Mall, Cork, Ireland T23 N73K